Compression RTM - A new ppgrocess for manufacturing · PDF fileCompression RTM - A new ppgrocess for manufacturing high volume continuous fiber reinforced composites ... resin transfer

Compression RTM - A new process for manufacturing p p ghigh volume continuous fiber reinforced composites

5th International CFK-Valley Stade Convention

07-08 June 2011, STADEUM Stade, Germany

Authors R Ch dh i Mi h l Pi kRaman Chaudhari, Michael Pick,

Oliver Geiger, Dennis Schmidt,

Prof Dr Ing Peter ElsnerProf. Dr.-Ing. Peter Elsner

Prof. Dr.-Ing. Frank Henning

Contents

Motivation and Goal of this Feasibility Study

State of the art: Resin Transfer Molding (RTM) ProcessState of the art: Resin Transfer Molding (RTM) Process

High Pressure RTM Processes

Definition of CRTM process parameters

Compression RTM process study

Process equipment

Experimental designExperimental design

Results and Discussion

Summary and Outlook

Acknowledgement

© Fraunhofer ICT

Motivation and goal of this feasibility study

Applications for high performance composite parts in the automotive industry

Side frameFloor structure

Audi R8 Spyder

Source:Alcan

RoofBumper BMW M6BMW M6

BMW Project I CityCar

Quelle: BMW

© Fraunhofer ICT

Quelle: BMW

Motivation and goal of this feasibility study

Development of a new processing strategy for the manufacturing of

high-performance thermoset composite parts in shorter cycle timeg p p p y

To overcome the issues of the standard resin transfer molding process

The new process strategy should fulfill the following requirements

Excellent material and part performance

Nice surface of the parts

Short cycle timesShort cycle times

Capable for the utilization of fast curing resins

Large scale production capability

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State of the art: Resin Transfer Molding (RTM) ProcessRTM Process cycle

3D PreformPreform production

and fixing

H dli i fi i h d

Preform handling

Mold technology

Fixing 2D-semifinished

Handling semi-finished product

gy

Infiltration and curing

Resin Hardener

gfabric product

and curing

Component demoldingand post processing

Textile product

Semi-finished fabric cuts 2D and post-processing

RTM componentMold cleaning

Start of cycle End of cycle

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State of the art: Resin Transfer Molding (RTM) ProcessRTM Process cycle – Injection sequence

The dry 3D fiber preform is placed into the open mold cavity and the mold cavity is closed completely (gap in the cavity = final wall thickness)cavity is closed completely (gap in the cavity = final wall thickness)

Resin and hardener are mixed and then injected into the cavity

Injected resin impregnates the preformInjected resin impregnates the preform

Demolding of the part after curing

Resin Hardener

Dry 3D fiber preform in completely closed mold

Resin injection, preform impregnation and curing of the part

Demolding of the cured RTM part

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completely closed mold and curing of the part cured RTM part

State of the art: Resin Transfer Molding (RTM) Process

Typical challenges and issues of the state of the art RTM process

Typical injection pressure between 1 and 20 barTypical injection pressure between 1 and 20 bar

Higher pressure disturbs the fiber orientation in the preform

Permeability of 3D fiber preform influences significantly the injection timePermeability of 3D fiber preform influences significantly the injection time

Proper impregnation of complex shaped preforms is a challenge

Required injection time does not allow the use of fast curing resin systems

Typically long cycle times due to long injection and curing times

Additional resin required to push trapped air out of the mold cavity

Negative economical and ecological impact

Probable solutions: High Pressure RTM processes

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High pressure injection RTM Process (HP-IRTM)HP Injection RTM Process cycle – Injection sequence

The dry 3D fiber preform is placed into the open mold cavity and the mold cavity is closed completely (gap in the cavity = final wall thickness)cavity is closed completely (gap in the cavity = final wall thickness)

Resin and hardener are mixed under high pressure and then injected into the cavity at leading to high pressure built up in the cavityy g g p p y

Injected resin impregnates the preform mainly due to flow in in x-y plane

Demolding of the part after curingg g

Resin Hardener

Dry 3D fiber preform in completely closed mold

Resin injection, preform impregnation and curing of the part


© Fraunhofer ICT

completely closed mold and curing of the part cured RTM part

High Pressure Compression RTM Process (HP-CRTM)Compression RTM Process cycle – Injection sequence

The dry 3D fiber preform is placed into the open mold cavity and the mold cavity is partially closedcavity is partially closed

Resin and hardener are mixed and injected into the mold gap at low cavity pressurep

The mold is then closed completely, high pressure is applied and the preform is completely impregnated and cured before demolding of the part

Resin Hardener

Dry 3D fiber preform in partially closed mold

Resin injection and partial preform impregnation

Apply pressure, complete preformimpregnation and curing of the part


© Fraunhofer ICT

p y p p g p g g p p

High Pressure RTM Processes

High Pressure Injection Resin Transfer Moulding

High Pressure Compression-Resin Transfer MouldingResin Transfer Moulding

HP-IRTMResin Transfer MouldingHP-CRTM

Impregnation of preforms in x- and y- direction

Impregnation of preforms in x-, y- and z- direction

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High Pressure Compression RTM Process (HP-CRTM)

Advantages and challenges of the Compression RTM process

Increased permeability of fiber preform due to open mold gapIncreased permeability of fiber preform due to open mold gap

Thus also reduced time for resin injection

Si ifi tl d d ti f f i ti th h hi hSignificantly reduced time for preform impregnation through high pressure

compression

Fast injection and impregnation allows the use of fast curing resins

Almost no additional resin required to push trapped air out of the mold cavity

Positive economical and ecological impact

Reduced cycle times (depending on part geometry, fiber architecture and

resin)

Challenge: Suitable mold technologies required (injection port, sealing etc.)

© Fraunhofer ICT

Definition of CRTM process parametersImportant process parameters affecting CRTM process

Fiber volume content

It can strongly affects the required compression force and the impregnation quality

Resin viscosity / Resin temperature

It can influences the impregnation quality in the CRTM process

Cavity pressure / Compression pressure

It can affect the impregnation beha ior in correlation to the resin iscosit and fiberIt can affect the impregnation behavior in correlation to the resin viscosity and fiber volume content

Mould gap and gap closure speed

It can mainly influence the impregnation during injection (mould gap) and flow of the resin in the cavity (gap closure speed) and hence the impregnation behavior

Injected resin amountInjected resin amount

It can mainly influence the impregnation during injection / degree of mould filling during injection

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Literature research to eventually derive process parameters

Fib l Cl i M ld C i R i I j ti I j ti M ld C itLiterature Fiber volume content

Closing speed

Mold temperature

Curing temperature

Resintemperature

Injection time

Injection pressure

Moldgap

Cavitypressure

[%] [mm/min] [°C] [°C] [°C] [s] [bar] [mm] [bar]

Kang, M. [1999]: "Analysis of resin transfer compression

molding process"24 27 27 27 2

Chang C [2006]: "Effect ofChang, C. [2006]: Effect of process variables on quality

of CRTM"25, 50, 75 80, 100, 120 25, 32, 40 1, 1.5, 2 1, 5,

10 1, 1.5, 2

lkegawa, N. [1996]: "Effect of compression process on 33 5 100 130 130 90 0 5 13 0, 3, 6,of compression process on void behavior in structural

resin transfer molding"

33 5, 100 130 130 90 0,5 13 0, 3, 6, 12

PHAM, X. [1999]: 1 5 3 0 90, 30- - 4 8 2

5.1 3.1

"Simulation of CRTM for thin shells"

18, 33 1.5, 3.0, 7.5, 15, 30 60, 14, 8,

8

-, 4.8, 2, 3.5, 7 (final

thickn.)

© Fraunhofer ICT


Process equipments

I j ti i tInjection equipment:

Wolfangel two-component RTM mixing and dosing equipment

Compression press:

Dieffenbacher DYL 630/500 hydraulic press, 6,300 kN press force

Compression RTM mold:

Plate mold 830 mm x 210 mm x 3 mm

© Fraunhofer ICT


Materials

Saertex non-woven fabric (S14EU960-01210-01300-487000)

UD

MC Sizing,

1218 g/m²

Epoxy resin system

Hexion RIM 935 and RIMH 936

Resin-/Hardener mixture:

100:29 (wt.-%) / 100:35 (Vol.-%)

Resin mixture viscosity: 340 mPa*sResin mixture viscosity: 340 mPa s

© Fraunhofer ICT


Experimental design

Fibre orientation

Resin temp.

Resin amount

Injection pressure

Cavity pressure Mould gap

Gap closure speed

Mould filling time

[°C] [g] [bar] [bar] [mm] [mm/s] [s]

RTM [04] RT --- 6-10 bar --- --- --- 400

CRTM 1 [0 ] RT 260 max 6 60 1 0 2 30 33CRTM 1 [04] RT 260 max. 6 60 1 0.2 30-33

CRTM 2 [04] RT 260 max. 6 60 2 0.2 30-33

RTM [0/90]s RT --- max. 6 --- --- --- 400[0/90]s a 6 00

CRTM 3 [0/90]s RT 260 max. 6 60 1 0.2 30-33

CRTM 4 [0/90]s RT 260 max. 6 60 2 0.2 30-33

© Fraunhofer ICT


Materials characterization program

ILSS samples 15mm x 30mmILSS samples 15mm x 30mm

Flexural test samples 15mm x 90mm

Fiber vol. content Ø 30 mm

Tensile test samples 15mm x 250mmp

2 4

1 33

2

5 46

51

12345

3

2

1

2

3

1 2

4

3

2

1

ILSS samples away from injection point ILSS samples close to injection point

© Fraunhofer ICT

Results and discussions

RTM experiments

N i t d P ti ll i t d f b iNon impregnated area Non impregnated areaPartially impregnated fabrics

It was not possible to obtain complete impregnation of the fibers even after 400s injection time in the classical RTM process at 6-10 bar injection pressure

Hence it was not possible to characterize the mechanical properties of the plates manufactured by the classical RTM process

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Tensile properties of the CRTM laminates1200 Tensile strength

45

50

Tensile modulus

800

1000

gth

[MPa

]

25

30

35

40

lus[

GPa

]

70

80

me -%

]


3

4 Part thickness

s (m

m)

1147 1131

596 561

45,85 46,12

31,82 30,77

200

400

600

Ten

sile

stre

ng

10

15

20

25

Ten

sile

mod

ul

58,51 60,05 59,37 61,15

30

40

50

60

Fibe

r vo

lum

cont

ent [

Vol

-

0

1

2

Part

thic

knes

s

Non crimp fabric[0 ]


Non crimp fabric[0/90]


Non crimp fabric [04]

CRTM

Non crimp fabric[04]

CRTM

Non crimp fabric[0/90]SCRTM


0

200

0

5

[04]CRTM

1mm Gap

[04]CRTM

2mm Gap

[0/90]SCRTM

1mm Gap

[0/90]SCRTM

2mm Gap

1mm Gap 2mm Gap 1mm Gap 2mm Gap

Nearly equivalent part thickness and hence fiber volume content was observed i th CRTM l i t t 1 d 2 ldin the CRTM laminates at 1 mm and 2 mm mold gap

Almost identical tensile properties of the CRTM laminates

© Fraunhofer ICT


Flexural properties of the CRTM laminates

1200

1400 Flexural strength

45

50

Flexural modulus

70

80

me -%

]


3

4 Part thickness

s (m

m)

800

1000

1200

gth

[MPa

]

30

35

40

58,51 60,05 59,37 61,15

30

40

50

60

Fibe

r vo

lum

cont

ent [

Vol

-

0

1

2

Part

thic

knes

s





1270 12281139

103737,27 37,5133,58 33,51

400

600

Flex

ural

stre

ng

10

15

20

25

[04]CRTM

1mm Gap

[04]CRTM

2mm Gap

[0/90]SCRTM

1mm Gap

[0/90]SCRTM

2mm Gap


CRTM


CRTM



0

200

0

5

10

Almost identical flexural properties of the UD CRTM laminates at both mold gaps

CRTM1mm Gap

CRTM2mm Gap

CRTM1mm Gap

CRTM2mm Gap

Flexural properties of [0/90]s laminates significantly high due to presence of UD layer from top and bottom side; a slight drop of flexural strength observed at 2 mm mold gap

© Fraunhofer ICT

g p


ILSS of the CRTM laminates ILSS Away from injection point

ILSS Close to injection point70

80

j p

50

60

70

Pa]

Fiber volume content (Away from Injection point)

Fiber volume content (Close to Injection point)

80

m]

4

Part thickness (Close to Injection point)

Part thickness (Away from Injection point)

59,35 58,83

34,87

57,89 57,58

32 71 33 4520

30

40

ILSS

[MP

58,92 60,39 58,08 63,7758,34 59,86 60,08 59,41Fibe

r vo

lum

e co

nten

t [V

ol-%

]

30

40

50

60

70

Part

thic

knes

s [m

m

0

1

2

3

34,8729,4532,71 33,45



Non crimp fabric[0/90]S

Non crimp fabric[0/90]S

0

10

30 0Non crimp fabric

[04]CRTM

1mm Gap


CRTM2mm Gap


1mm Gap


2mm Gap

Almost identical ILSS properties for UD laminates at 1 mm and 2 mm mold gap b d i j ti i t d f i j ti i t

4CRTM

1mm Gap

4CRTM

2mm Gap

SCRTM

1mm Gap

SCRTM

2mm Gap

observed near injection point and away from injection point

At 2 mm mold gap the ILSS properties of bidirectional laminates dropped slightly for the samples away from injection point if compared to close to injection point

© Fraunhofer ICT

p y j p p j p

SummaryThe CRTM process was investigated using 1 mm and 2 mm mold gap

The unidirectional ([0]4) and bidirectional ([0/90]s) laminate layup were used for

investigating the effect of chosen mold gaps on the CRTM process

The selection of 1 mm or 2 mm mold gap did not show any influence on the tensile and

flexural properties of the UD and bidirectional CRTM laminates

For bidirectional laminates at 1mm and 2 mm mold gap, depending on the degree of

mold filling after injection step, roving displacement and bad impregnation quality was

observed due to resin flow under compression force, solution reduction of resin

i itviscosity

CRTM process utilizes only the required amount of the resin which has a direct impact

on environment and process economyon environment and process economy

Due to very low resin injection time and impregnation time the CRTM process indicates

high potential for high volume manufacturing

© Fraunhofer ICT

high potential for high volume manufacturing

Outlook

Ongoing activities

Evaluation of different fabric architectures and fiber orientation on the CRTMEvaluation of different fabric architectures and fiber orientation on the CRTM

process development

Evaluation of effect of compression pressure on CRTM process developmentEvaluation of effect of compression pressure on CRTM process development

Use of highly reactive resins to manufacture laminates in less than 5 min cycle

time in the mould

Setting up automated Compression RTM infiltration setup using KraussMaffei

High Pressure RTM equipment for industrial scale manufacturing

© Fraunhofer ICT

OutlookOngoing activities

Development of the industrial scale High Pressure Compression RTM processp g p p

Prototype study:

Resin injection time: 7.5 sec

Impregnation time: 5-10 sec

Cure cycle time: 4 min

part size: 830x210x3 mmpart size: 830x210x3 mm

Fiber vol. content: ca. 57-60%

Prototype sample

© Fraunhofer ICT

Acknowledgement

"Dieses Vorhaben wird durch die Europäische Union - Europäischer Fonds für regionale

Entwicklung - sowie das Land Baden-Württemberg gefördert. Verwaltungsbehörde des

operationellen Programms RWB-EFRE ist das Ministerium für Ländlichen Raum,

E äh d V b h h B d Wü b W i I f iErnährung und Verbraucherschutz Baden-Württemberg. Weitere Informationen unter

www.rwb-efre.baden-württemberg.de“

© Fraunhofer ICT

Compression RTM - A new process for manufacturing p p ghigh volume continuous fiber reinforced composites

5th International CFK-Valley Stade Convention

07-08 June 2011, STADEUM Stade, Germany

Thank you very much for your kind attentionThank you very much for your kind attention.

Contact:

Raman ChaudhariRaman Chaudhari

Fraunhofer ICT

raman chaudhari@ict fraunhofer [email protected]

Documents

Compression RTM - A new ppgrocess for manufacturing · PDF fileCompression RTM - A new ppgrocess for manufacturing high volume continuous fiber reinforced composites ... resin transfer